According to the prior art of a dead blow hammer disclosed in U.S. Pat. No. 6,595,087, its head tube is filled with specific amount of rigid pellets which are rollable within the tube. Both distal ends of the head have an opening and two end caps are fitted respectively inside the open ends of the head tube for closure. On one side of the head tube is vertically extended a neck tube in its center portion to integrate with a handle to form a complete hammer.
There are certain disadvantages from the prior art:
1. The rigid pellets are made of single material which cannot effectively inhibit their rebound.
2. The movement of the pellets is unpredictable and unstable due to the bulky head tube. Because of the unpredictable rebound of the pellets, it is easy to hurt user's hand.
3. Inasmuch as the pellets dash against each other in the head tube, the rigid surfaces of the pellets are easy to be damaged. The movement of the pellets is consequently hindered, and the function of shock absorbing is relatively decreased.
4. The head tube is hollow with shell structure which is not durable enough to bear external striking force.